(1) Field of the Invention
The present invention relates to a nut feeder for feeding nuts to nut resistance welding equipment and broadly to a nut feeder for feeding nuts to a predetermined position.
(2) Description of Related Art
Japanese Unexamined Patent Publication No. 2002-321064 shows an example of nut feeders for feeding nuts to nut resistance welding equipment. In this nut feeder, a push rod is provided at its front end with a nut support pin and connected to the front end of a rod of an air pressure cylinder serving as an actuator. The push rod is placed in a rod holder concentrically attached to the front end of the actuator. The pushing operation of the air pressure cylinder moves the push rod forward to thereby feed to the target position of a workpiece a nut held by the support pin at the front end of the push rod.
However, since in the above-described nut feeder the air pressure cylinder is used as the actuator, an air compressor for feeding air needs to be installed in a factory. In this case, enormous amounts of electric power are consumed to operate the compressor, and air piping in the factory becomes complex. In addition, sounds resulting from the air compressor and other pneumatic equipment provide noises, leading to the deterioration in working environment.
To cope with this, in recent years, electric cylinders have been used as actuators as described above to attempt to save energy and reduce noises.
Meanwhile, the present inventors have invented and put into practice use an apparatus and a method for blowing air out of the front end of a nut feed rod toward a nut to hold the nut on the rod using the air pressure in order to prevent the nut from accidentally dropping off the front end of the nut feed rod, as described in Japanese Laid-Open Patent Publication No. 10-43870.
Hence, removal of the air compressor from the factory would preclude the application of nut holding means utilizing this kind of air pressure. This makes it difficult to save energy totally in the factory.